The process water stripping tower for the 220 kt/a ethylene plant of PetroChina Dushanzi Petrochemical Company had problems such as clogged packing and poor packing at the end of its operation. The operation was optimized by adding level gauges to the process water stripping tower, increasing the scale removal frequency of the system and injecting dispersant, so as to solve or alleviate the blockage in the packing layer of the process water stripping tower. Through online isolation and repair of the process water stripping tower, the operation bottleneck of process water system was solved.